Wound treatment device employing negative pressure

ABSTRACT

The present invention provides a device for wound treatment, comprising a chamber that includes an inner surface and defines a treatment space, the chamber being made of a flexible, impermeable material. The device further includes a plurality of structures configured to exert mechanical stress on a wound, the plurality of structures intruding from the inner surface of the chamber into the treatment space. The device further includes a tube having a first end connected to the chamber, the tube being in fluid communication with the treatment space so as to enable at least one selected from the group of applying negative pressure to the treatment space and applying a therapeutic agent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/601,394 (now U.S. Pat. No. 8,632,523) filed Sep. 20, 2010, which is a371 of PCT International Application No. PCT/US2008/064897 filed May 27,2008, which claims the benefit of U.S. Provisional Patent ApplicationNo. 60/931,559 filed May 24, 2007, each of which is incorporated hereinby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The invention relates generally to the field of wound treatment, andmore particularly, to a device for treating wounds with negativepressure and/or therapeutic agents.

BACKGROUND OF THE INVENTION

Many wounds can be treated by the application of negative pressure. Themethod of such treatment has been practiced for many years. The benefitsof such treatment can include: reduction of edema; reduction of woundexudate; reduction of wound size; and stimulation of formation ofgranulation tissue. Existing devices and appliances for the provision ofnegative pressure wound therapy are complex. Such devices typicallyencompass a porous insert such as foam or gauze that is placed into thewound; a tube connecting the insert to a source of suction; a flexiblecover draped over these components and sealed to the skin around thewound; an electrically powered suction pump; controls to operate thepump and monitor the system; containers to collect wound fluids; filtersto process the materials removed from the wound; and safety systems toprevent harm to the patient and to block the escape of biologicalmaterials into the outside environment. These devices are expensive,labor intensive, and restrictive of patient mobility. The manycomponents, particularly the seals around the insert and the tube, tendto leak. Therefore, suction must be applied either continuously orfrequently.

Continuous suction is typically achieved by a vacuum pump powered by anelectric motor. Such systems require complex means to measure, monitor,and control the operation of the pump to ensure the safety of thepatient. In addition, many negative pressure devices are contraindicatedin the presence of necrotic tissue, invasive infection, active bleeding,and exposed blood vessels. They require the use of a porous insert(sponge, foam, gauze, mesh, etc.) in the wound. The insert may presenttwo problems: growth of tissue into the insert, and the harboring ofinfectious and/or undesirable materials in the insert. Wound tissue cangrow into and around such inserts, thereby causing adverse results tothe healing process. Moreover, such inserts can retain wound fluid andmicroorganisms, and therefore can become contaminated and/or infected,presenting an adverse effect to the healing process. In addition, thehigh cost of these devices may deter or delay their use on patients.

Existing negative pressure treatment devices are labor intensive sincethey require the user to assemble, fit, and customize a number ofcomponents. First, the user must prepare, trim, and size an insert offoam, gauze, mesh, or other material that will be placed in the wound.Next, the user must position a tube in the insert, and then cover thetube and insert with a material that is intended to create a leakproofseal. In practice, and as mentioned above, such compositions tend toleak, requiring the frequent application of suction in order toestablish and re-establish negative pressure within the space about thewound. In addition, currently available negative pressure devices andsystems block the view of the wound, making monitoring and diagnosismore difficult. Therefore, an improved device for applying negativepressure to wounds is needed.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention is summarized as a device for woundtreatment, comprising a chamber that includes an inner surface anddefines a treatment space, the chamber being made of a flexible,impermeable material. The device further includes a plurality ofstructures configured to exert mechanical stress on a wound andconfigured to create pathways through which negative pressure can bedistributed and maintained in the treatment space, the plurality ofstructures intruding from the inner surface of the chamber into thetreatment space. The device further includes a tube having a first endconnected to the chamber, the tube being in fluid communication with thetreatment space so as to enable at least one selected from the group ofapplying negative pressure to the treatment space and applying atherapeutic agent.

In some embodiments, the plurality of structures and the chamber arepart of a single ply of material. In addition, in some embodiments, eachof the structures in the plurality of structures is semi-rigid.

In some embodiments, the device includes a wedge-shaped manual pump, andthe treatment space is in fluid communication with the wedge-shapedmanual pump. The wedge-shaped manual pump may include a spring thatbiases the wedge-shaped manual pump to an uncompressed position.

The foregoing and other objects and advantages of the invention willappear in the detailed description that follows. In the description,reference is made to the accompanying drawings that illustrate apreferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the followingdescription taken in conjunction with the accompanying figures, in whichlike reference numerals identify like elements. It should be understoodthat figures represent an example of the present invention andcomponents are not necessarily shown to be proportional to one another.The terms “chamber wall” or “wall” mean any part of the chamber devicethat forms or encloses the chamber treatment space. The term “overview”means a view from the inside of the chamber treatment space lookingtoward the interior surface of the chamber wall.

FIG. 1 is a perspective view of a wound chamber treatment device with atube leading from a chamber to a suction source;

FIG. 2 is a side sectional view of the device in FIG. 1;

FIG. 3 is a sectional view of the device in FIG. 1 with an additionaltube leading to a port;

FIG. 4 is a sectional view of the device in FIG. 1 with a branching tubeleading to a port;

FIG. 5 is a perspective view of the end of the tube communicating withthe interior chamber space;

FIG. 6 is a side sectional view of structures engineered on and into theinterior surface of the chamber wall, where the structures are ofuniform size and shape, and are spaced uniformly apart;

FIG. 7 is a side sectional view of two groups of structures engineeredon and into the interior surface of the chamber wall, where one groupintrudes into the chamber space, the other group intrudes to a lesserextent, and structures from these groups alternate in a regular pattern;

FIG. 8 is a side sectional view of three groups of structures engineeredon and into the interior surface of the chamber wall, where such groupshave varying degrees of intrusion into the chamber space and alternatein a regular pattern;

FIG. 9 is an overview of structures engineered on and into the interiorsurface of the chamber wall, where the structures consist of raisedridges;

FIG. 9a is a side sectional view of the raised ridges of FIG. 9 withrounded edges;

FIG. 9b is a side sectional view of the raised ridges of FIG. 9a withsquare cross sections;

FIG. 10 is an overview of the raised ridge structures shown in FIG. 9,with the addition of raised dome structures positioned among the ridges;

FIG. 11 is an overview of raised ridge structures engineered on and intothe interior surface of the chamber wall, where two parallel lines ofsuch structures form a channel;

FIG. 12 is an overview of raised dome structures engineered on and intothe interior surface of the chamber wall, where two parallel lines ofsuch structures form a channel;

FIG. 13 is a view of a wound chamber, showing a pattern of channelsleading to the center of the chamber and then to the tube communicatingfrom the interior of the chamber space;

FIG. 14 is a view of a radiating pattern of channels leading to thecommunicating tube;

FIG. 15 is a view of a branching pattern of channels leading to thecommunicating tube;

FIG. 16 is a view of a sub-branching pattern of channels leading to thecommunicating tube;

FIG. 17 is a side sectional view of a fold in the chamber wall;

FIG. 18 is a side sectional view of a fold in the chamber wall, withstructures engineered on and into the inner surface of the fold, whichstructures maintain continuous open space within the fold;

FIG. 18a is a side sectional view of the fold in the chamber wall ofFIG. 17 with structures engineered on the inner surface of the fold;

FIG. 19 is a view of a wound chamber configured as a tube for placementover a limb, and having engineered structures and channels on theinterior surface of the chamber wall;

FIG. 20 is a sectional view of the device in FIG. 1 showing a fluidcollector placed before the suction source;

FIG. 21 is a sectional view of a suction device in the form of a squeezebulb of deformable material;

FIG. 22 is a sectional view of a suction device in the form of aflexible chamber containing one or more compression springs;

FIG. 23 is a sectional view of a suction device in the form of awedge-shaped chamber containing one or more torsional springs;

FIG. 24 is a sectional view of the device in FIG. 23 containing a flatspring; and

FIG. 25 is a sectional view of a suction device with a trap and filterincorporated into the exhaust port.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are described below in detail. It shouldbe understood, however, that the description of specific embodiments isnot intended to limit the invention to the particular forms disclosed,but on the contrary, the intention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While the present invention may be embodied in any of several differentforms, the present invention is described here with the understandingthat the present disclosure is to be considered as setting forth anexemplification of the present invention that is not intended to limitthe invention to the specific embodiment(s) illustrated.

The present invention is directed to providing a simple, safe,disposable, and cost-effective device that is easy to install andoperate, that allows freedom of motion to the patient, and thatovercomes, or at least reduces the effects of, one or more of theproblems set forth above. The present invention does not require the useof a porous insert. The one-piece construction of the device eliminatesvirtually all leaks, therefore preserving and maintaining negativepressure within the wound without the need for constant or frequentregeneration of negative pressure. In addition, the structure of thedevice is configured to promote wound healing and to create pathwaysthrough which negative pressure can be distributed and maintained in thetreatment space. The indications for the present invention may beexpanded beyond the limitations imposed on current devices. Thecost-effectiveness of the present invention may lead to the provision ofnegative pressure wound therapy on a more widespread basis and earlierin the timeline of wound care.

One aspect of the present invention is seen in a wound treatment deviceincluding a chamber defining a treatment space around the wound. Theflexible adhesive base of the chamber forms a water-tight and gas-tightseal. A tube communicates from the treatment space to a source ofsuction. The suction source also serves as a receptacle for materialsremoved from the chamber. All components preferably are inexpensive,lightweight, and disposable.

Referring first to FIGS. 1 and 2, views of a wound treatment device 20are provided. The device 20 includes a chamber 22 defining a treatmentspace 24 and a base 26 that may be sealed to a skin surface 28 of apatient over a wound 30. In the illustrated embodiment, the chamber 22has a bellows configuration with a fold 23. However, the invention isnot so limited, and other configurations of a chamber formed of aflexible, moisture and gas impermeable material may be used. Materialsfrom which the device 20 may be made will be discussed in further detailbelow. The device 20 can be designed for use with any wound or bodypart, using circular, square, rectangular, tubular, pouch, envelope orother shapes. For example, a chamber in the form of a tube or sleeve forplacement over a limb is shown in FIG. 19. Referring again to FIGS. 1and 2, a dermal or cutaneous adhesive material may be provided on abottom surface of the base 26 for providing a fluid-tight seal withsufficient adhesive strength to prevent inadvertent removal of thechamber 22 or breach of the fluid-tight seal during normal patientmovement. Numerous adhesive materials sufficient for these purposes areknown to those of ordinary skill in the art.

A tube 32 is attached to the chamber 22 preferably at a location spacedabove the base 26 and communicates with the treatment space 24. The tube32 is constructed to maintain its shape without collapsing and to permitthe passage of wound fluids and wound debris. The tube 32 may bepermanently fixed to the chamber 22, or a fitting 25 may be provided toallow the attachment and removal of the tube 32 or any other device thatcan deliver material or therapies to, or remove material from, thetreatment space 24. The tube 32 may terminate at a wall of the chamber22, or it may extend through the wall a distance and terminate withinthe treatment space 24, where it may communicate with such space, withchannels formed on the inner surface of the chamber wall, or with foldsformed in the chamber wall. The tube 32 is sealed to the chamber 22 insuch a manner as to prevent the escape of liquid or gas from thetreatment space 24 to the outside environment. A distal end of the tube32 terminates at a suction device 34. The suction device 34 may be apump, although other types of devices may be used as discussed below. Afitting 33 may be provided to permit the detachment and reattachment ofa suction device 34 to the tube 32.

Turning to FIG. 3, a sectional view of the device 20 is provided,showing a second tube 35 attached to the chamber 22 and communicatingwith the treatment space 24, with channels, or with folds. A distal endof the tube 35 terminates in a portal 36. The invention is not limitedto any number of communicating tubes, and multiple tubes and portals maybe provided for accessing the treatment space 24. FIG. 4 shows thedevice in FIG. 1 with a branch of the tube 32 that leads to a portal 36.The portal 36 may be used for the delivery of therapeutic agents—such asantimicrobials, antibiotics, antifungals, and analgesics—prior to,during, or after the delivery of negative pressure. As such, the portal36 may be a lure configured for attaching to a container or a syringe.Alternatively, therapeutic agents may be delivered through the same tube32 that communicates with the suction device 34.

Turning now to FIG. 5, the end of the tube 32 extending into the chamberspace 24 is shown with multiple holes [apetures?] 44. The purpose of theholes 44 is to ensure that gases, liquids, wound fluid, debris, andother materials can flow and move out of the chamber space 24 into thetube 32 without impediment.

Referring to FIG. 6, the interior surfaces of the chamber wall may beconfigured with structures 40 that are engineered on the surfaces. Theportions of the interior surfaces with engineered structures 40 may bevaried from that shown in the figures, and preferably a high percentageof the interior surfaces include engineered structures 40. Thestructures preferably cover at least 50% of the interior surfaces, andmore preferably at least 95% of the interior surfaces. These structuresare raised when viewed from within the chamber space 24, and theyintrude into such space in directions generally perpendicular to theinterior surfaces of the chamber space 24. These structures can be anyshape, including without limitation a cone, a pyramid, a pentagon, ahexagon, a half sphere, a dome, a rod, an elongated ridge with roundedsides, or an elongated ridge with square sides. The structures can beprovided as identical shapes, or in any combination of shapes. Thestructures can be provided with identical sizes, or in any combinationof different sizes. The distance of intrusion into the chamber treatmentspace 24 from the chamber wall by such structures is preferably between0.01 mm and 20 mm, and is more preferably between 1 mm and 1 cm. Thespacing between such structures is preferably between 0.01 mm and 5 cm.

The engineered structures 40 interface with the wound surface during useof the device 20. One purpose of these structures is to ensure thatnegative pressure established within the chamber space 24 is evenlydistributed and maintained throughout such space. As negative pressureis established within the tube that leads to the source of suction, thechamber will lie tighter against the wound tissue. The device 20includes the engineered surfaces 40 in order to define pathways toestablish, distribute, and maintain negative pressure across the woundsurface and prevent complete contact between the inner surfaces of thechamber and the wound tissue. Without such structures, the chamber wallwould make complete contact with the wound surface. As a result, therewould be no space within which negative pressure could be established,distributed, and maintained. Therefore, the engineered structures arepreferably semi-rigid. The term “semi-rigid” should be understood asmeaning that deformation only occurs at a microscopic level underoperating negative pressures in the range of 0.5-2 psi. Alternatively,the engineered structures may be somewhat flexible depending on thespacing between the structures. In addition, the structures areengineered to reduce the extent to which wound tissue can enter thespace between the structures, so that a sufficient amount of open spaceis maintained.

An additional purpose of these structures is to serve as a form ofstimulation to the wound to produce beneficial results, includingwithout limitation the formation of granulation tissue and an increaseof micromechanical forces. Such mechanical forces provide stimulation toa portion of the wound tissue, which has been suggested as acontributing factor to the effectiveness of negative pressure woundtherapy. From the above discussion and the figures, it should beunderstood that the flexible chamber is movable over a range ofpositions. The range of positions includes a first position, such as theposition shown in FIGS. 1 and 2, in which the engineered structures 40are spaced apart from the opening of the chamber defined by the base 26.The range of positions also includes a second position in which at leastsome of the engineered structures 40 are positioned in the opening ofthe chamber. The second position is preferably a position in which theengineered structures 40 engage the wound.

The chamber wall can be formed of any appropriate medical grade materialthat has the following characteristics: flexibility, conformability, gasimpermeability, liquid impermeability, the ability to be formed, tooled,and engineered, and the ability to retain the shape, function, andeffectiveness of raised structures under desired ranges of negativepressure. In addition, the material is preferably hypo-allergenic andprovided to a medical facility in a sterile condition. For example, thechamber device may be made of a flexible, conformable material such aspolyurethane, although other similar materials may also be used. Thechamber is preferably designed to provide sufficient material to lieagainst the surface of the wound tissue without special sizing,trimming, or other customizing operations. The chamber may be made froma single ply of material, or may be constructed of multiple layers ofmaterial in and on which the structures are engineered. It should beunderstood that a single ply chamber may be made of multiple sheets ofmaterial during manufacturing, but is provided to a medical facility ina state in which the multiple sheets are bonded or otherwise connectedto one another. For example, individual three dimensional shapes may beadhered or bonded to the inner surface of the chamber wall duringmanufacturing to provide the engineered structures. A single ply chambercould also be formed from a single sheet of material that defines boththe chamber walls and the engineered structures. Alternatively, amultiple layer chamber is provided to a medical facility in a state inwhich layers of material are stacked to form the chamber. For example,the layer facing the interior treatment space of the chamber could be alayer containing engineered structures that is bonded onto a generallyflat layer of material (or multiple sheets of generally flat layers) bya medical practitioner.

The engineered structures can be made by techniques familiar to those inthe art, such as embossing, stamping, molding, forming, or bonding. Ifthe structures are created by embossing their shape into the material,the embossed structures may be left in a concave state relative to theoutside of the chamber as shown in FIG. 6. Embossed structures may alsobe formed on a single ply of material that also forms the walls of thechamber and the base. This may provide a chamber that is relativelyflexible and semi-rigid structures on a single ply of material.Alternatively, the cavities may be filled with a suitable material torender the structures solid. As another alternative, solid structurescan be affixed to the inner surfaces of the chamber.

The raised structures on the inner surfaces of the chamber wall can beconfigured and distributed in a number of patterns. For example, FIG. 6is a side sectional view of a portion of a chamber wall, showingengineered structures 40 on the interior surface of the material thatfaces treatment space 24. Structures 40 are identical in shape and size,and are positioned uniformly apart from one another. As another example,FIG. 7 is a side sectional view showing engineered structures 41 and 42intruding into the chamber space, where structures 41 intrude fartherthan structures 42, and the structures are configured in a regularalternating pattern of 41-42-41-42 and so forth. As yet another example,FIG. 8 is a side sectional view showing engineered structures 43, 44,and 45 intruding into the chamber space, where structures 43 intrudefarther than structures 44 and 45, structures 44 intrude less thanstructures 43 but farther than structures 45, and structures 45 intrudeless than structures 43 and 44. These structures are configured in aregular alternating pattern of 43-45-44-45-43-45-44-45-43 and so forth.The embodiment shown in FIG. 8 makes it difficult for soft wound tissueto penetrate all of the spaces among the raised structures. A sufficientamount of continuous space is established to make possible thedistribution of negative pressure, as well as the addition of fluids andtherapies and the removal of fluids and materials from the wound. As yetanother example, FIG. 9 is an overview of a portion of the chamber wall,showing engineered structures 47 in the form of raised ridges. Theengineered structures 47 may be rounded (FIG. 9a ), square (FIG. 9b ),or a combination thereof when viewed from the side. As yet anotherexample, FIG. 10 is an overview showing engineered dome structures 48interspersed with ridge structures 47. The engineered dome structures 48are preferably semi-spherical when viewed from the side, although othershapes are contemplated.

The distribution and maintenance of negative pressure within the chamberdevice and at all points on the wound may be enhanced by providingdefined channel spaces as pathways among the raised engineeredstructures for the distribution of negative pressure. However, definedchannel spaces are not required for providing fluid pathways within thetreatment space. FIG. 11 is an overview of a portion of the chamberwall, showing structures 47 arranged in two parallel lines to formchannel 49. FIG. 12 shows a channel 49 formed by two parallel lines ofraised domed structures 48. Such channels can be configured in variouspatterns, such as radial, circular, concentric, or branching. FIGS.13-16 show overviews of patterns of channels 49 leading from tube 32along the interior surface of chamber 22 facing treatment space 24. Foreach pattern, the channel 49 defines a space that opens directly to thetreatment space 24. The space preferably opens to the treatment space 24over the entire length of the channel 49.

The distribution and maintenance of negative pressure with the chamberdevice and at all points on the wound can also be enhanced by the use offolds in the chamber wall to create additional channel space for thedistribution of negative pressure. When negative pressure is establishedwithin the chamber, the material will tend to fold along the pre-formedlocation. FIG. 17 shows a channel 50 formed in a fold of the chamberwall. The channel 50 defines a space that opens directly to thetreatment space 24. The space preferably opens to the treatment space 24over the entire length of the channel 50. In order to increase theamount of channel space within such fold, the walls of the fold can beconfigured with structures that prevent the collapse of such space, andensure continuous open space for the distribution and maintenance ofnegative pressure, and the passage of liquid, gas, and other material.As an alternative, FIG. 18 shows engineered structures 52 that preventthe total collapse of the fold, and ensure continuous channel space 51.All channel spaces created on the interior surface of the chamber wallor by means of folds function as means to increase the effectiveness ofdistributing and maintaining negative pressure within the chamber, andalso as means to enhance the effectiveness of removing gas, liquid,wound fluid, debris, and other materials from the chamber treatmentspace. As another alternative, FIG. 18a shows an embodiment similar tothe embodiment shown in FIG. 17 with the addition of engineered raisedstructures 52 on opposite sides of the fold. The engineered structures52 are provided so that the fold will not collapse to the point whereall of its interior surfaces form a tight seal against the movement ofnegative pressure. However, some of the interior surfaces, such as thoseadjacent to the fold, preferably contact the wound to providestimulation as discussed above. The folds described in the previousembodiments are preferably formed at certain defined areas by molding orembossing the surfaces of the chamber 22.

FIG. 19 shows a wound chamber device 120 for delivering negativepressure and therapeutic substances in the form of a tube that can beplaced over a limb. The wound chamber device 120 is generallycylindrical and includes an open end and a closed end. The open end ispreferably sealed with a cuff or collar (not shown), and the open endmay include adhesive on the interior surface. The wound chamber device120 includes engineered structures 40 and channels 49 on the interiorsurface of the chamber wall.

As shown in FIG. 20, a fluid collector 60 may be positioned on the tube32 between the chamber 22 and the suction device 34. The collector 60 isintended to receive fluid extracted from the chamber space 24 and debrisor material from the wound and store such materials for eventualdisposal. The collector 60 may be detachable from the tube 32, in orderto replace a full collector with an empty collector.

Suction for the wound treatment device is provided by a suction device34, which may be a pump that is connected and disconnected to thechamber device by appropriate connectors. Although the wound chamber canbe used with a motor driven pump, it is also effective with ahand-powered device actuated by the caregiver or patient. Thehand-powered device may be a squeeze bulb that provides suction by meansof the energy stored in the material of its construction. Alternatively,the suction device may be powered by springs that are compressed by theuser. The springs can be selected to produce the clinically desiredlevel of negative pressure. The amount of suction provided by thesesuction devices is therefore dependent on the level of force generatedby squeezed material or the springs. Unlike a motor driven suction pump,the hand powered device preferably cannot produce a high level ofsuction that may cause an adverse effect to wound healing.

Referring to FIG. 21, a suction device 61 in the form of a bulbconstructed of a deformable material that stores the energy ofdeformation may be used. The tube 32 communicates with the interior ofthe suction device 61. A one-way exhaust valve 62 also communicates withthe interior of the suction device 61. When the user squeezes thesuction device 61, air within the device is expelled through the exhaustvalve 62. A portion of the energy used to deform the suction device 61is stored in the material of which it is constructed, thus maintainingsuction within the device, as well as within the tube 32 and the chamberspace 24. The bulb is selected and engineered to maintain a constantforce and to maintain the clinically desired level of negative pressurewithin chamber space 24. Fluid from the wound 30 can flow through thetube 32 into the suction device 61 where it can be stored prior todisposal. Once the suction device is full of fluid, the production ofnegative pressure ceases. The fluid capacity of the suction device thusoperates as a safety shut-off mechanism without the need for electronicsensors and controls.

FIG. 22 shows an alternative suction device 63, consisting of flexiblesides 64 and rigid sides 65. Compression springs 66 are located withinsuction device 63. The tube 32 and the exhaust valve 62 both communicatewith the interior of the suction device 63. When the user squeezes therigid sides 65 towards one another, the springs 66 are compressed andair within the device is expelled through a one-way exhaust valve 62thus maintaining suction within the device, as well as within the tube32 and the chamber space 24. The springs 66 are selected and engineeredto maintain a constant force against rigid sides 65, and to maintain theclinically desired level of negative pressure within chamber space 24.Fluid from the wound 30 can flow through the tube 32 into the suctiondevice 63 where it can be stored prior to disposal of the entire device63. This suction device will also cease operating when it is filled withfluid.

FIG. 23 shows an alternative suction device 70, consisting of rigidsides 72, joined by hinge 73, and flexible side 71. A torsional spring74 is attached to either the interior or the exterior of rigid sides 72.The tube 32 and the exhaust valve 62 both communicate with the interiorof the suction device 70. When the user squeezes the rigid sides 72towards one another, the spring 74 is compressed and air within thedevice is expelled through a one-way exhaust valve 62, thus maintainingnegative pressure within the device, as well as within the tube 32 andthe chamber space 24. The spring 74 is selected and made to maintain aforce against rigid sides 72 to maintain the clinically desired level ofnegative pressure within chamber space 24. Fluid from the wound 30 canflow through the tube 32 into the suction device 70 where it can bestored prior to disposal of the entire device. FIG. 24 shows the deviceof FIG. 27 where the torsional spring 74 has been replaced by a flatspring 78.

For the previous suction devices, once suction has been established,fluid may flow from the wound to the suction device, where it may becollected and stored for eventual disposal. Alternatively, a separatefluid collector, such as the fluid collector 60 in FIG. 20, can bepositioned between the chamber and the suction device. Once the suctiondevice has expanded to its original shape, suction ceases. The suctiondevice will not continue to operate, and can be disconnected anddisposed of. If treatment is to be continued, a new suction device canbe connected and activated.

FIG. 25 is a sectional view of a trap 80 and a filter 82 interposedbetween the suction device 34 and the exhaust valve 62 for the purposeof preventing the expulsion of liquids or aerosols from the suctiondevice.

The present invention can be engineered to operate at various levels ofnegative pressure, in accordance with clinical procedures. Historically,the commonly accepted range of negative pressure is between 0.5 and 2psi. The device of the present invention operates efficiently in thisrange. The chamber material conforms to the shape of the wound, and theembossed projections maintain their shape and functionality. However,the chamber can be engineered to operate at higher levels of negativepressure. In addition, if a hand-powered suction device is used, theoperating pressure of the device may be higher than the commonlyaccepted range; that is, the device may operate at a pressure close to 0psi before suction ceases.

The effectiveness of the raised structures in distributing andmaintaining negative pressure within the chamber and across the woundsurface has been demonstrated in a test model. A wound was created in asample of animal cadaver tissue. A pressure sensor was installed in thetissue at the center of the wound. A wound chamber device with raisedengineered structures on the interior chamber wall was sealed to theskin around the wound. A tube from the chamber device was connected to asource of suction capable of delivering a range of negative pressure.The amount of negative pressure measured at the suction source wascompared to the measurement at the center of the wound, in order todetermine the effectiveness of the device with respect to thedistribution of negative pressure to the wound. The following valueswere obtained:

Pressure at Source (mmHg) Pressure in Wound (mmHg) −80 −65 (81.25%efficiency) −100 −86 (86.00% efficiency) −120 −100 (83.33% efficiency) 

The raised structures were observed to maintain their shape with nodeformation, thereby preserving their functionality.

The operation of the invention may be illustrated by the following case.A patient with a full-thickness skin wound was treated with a woundchamber negative pressure device connected to a hand-powered suctionpump. The interior surface of the chamber contained embossed raisedstructures. The area around the wound was treated with normal skindisinfectants. The backing from the adhesive base of the chamber wasremoved, and the chamber was sealed to the normal skin around the wound.The tube was connected to a modified squeeze bulb with an inlet port forfluid, and an exhaust port through which air can be expelled from thebulb. By squeezing the bulb down to its flattest configuration, anegative pressure of 2 pounds per square inch was established andmaintained within the chamber. After the first twenty-four hours oftreatment, the squeeze bulb had expanded to approximately half of itsnormal size. The bulb was compressed again to its fully flattenedconfiguration. The bulb remained in such configuration for an additionaltwelve hours, at which point the chamber was removed. The wound showedhealthy granulation tissue and progressed to heal rapidly and withminimal scarring. The device produced no adverse effects on the wound orthe surrounding skin.

The present invention eliminates many of the drawbacks to existingnegative pressure wound therapy systems. For example, the device of thepresent invention is preferably simplified and lightweight. In someembodiments of the invention, the patient is not restricted to a sourceof electricity or a battery pack. The system can be worn with ease, sothat the patient's mobility is not otherwise compromised. In addition,the wound interface appliance can be applied quickly without the needfor custom fitting and construction. The device preferably does not leakdue to the smooth adhesive base, eliminating the need for constantsuction from an electric pump with sophisticated controls and safetymeasure. There is no porous wound insert that can potentially causetissue in-growth and harbor infectious material. Instead, the innersurfaces of the chamber are generally non-porous and non-adherent toprevent any interaction with the wound tissue. Further still, thesuction pump preferably has built-in safety limitations on force ofsuction, duration of operation, and overfilling of the collector forwound fluid.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Furthermore, no limitations are intended to thedetails of construction or design herein shown, other than as describedin the claims below. It is therefore evident that the particularembodiments disclosed above may be altered or modified and all suchvariations are considered within the scope and spirit of the invention.Accordingly, the protection sought herein is as set forth in the claimsbelow.

The invention claimed is:
 1. A device for wound treatment, comprising: a chamber being made of an impermeable material, the chamber having: an inner surface that defines a plurality of structures configured to directly contact a wound and to create pathways for distributing negative pressure between the inner surface and the wound; and a sealing portion that along with the inner surface defines a sealed treatment space around the wound, the plurality of structures intruding into the sealed treatment space from the inner surface of the chamber; and a tube having a first end connected to the chamber, the tube being in fluid communication with the sealed treatment space so as to enable at least one of applying negative pressure to the sealed treatment space and applying a therapeutic agent to the wound, wherein the chamber does not include a porous insert.
 2. The device of claim 1, wherein the plurality of structures are arranged in a pattern to define the pathways on the inner surface of the chamber.
 3. The device of claim 1, wherein the plurality of structures intrudes into the sealed treatment space in a direction generally perpendicular to the inner surface.
 4. The device of claim 1, wherein each structure has a shape selected from the group consisting of a cone, a pyramid, a pentagon, a hexagon, a half sphere, a dome, a rod, an elongated ridge with rounded sides, and an elongated ridge with square sides.
 5. The device of claim 1, wherein each structure is semi-rigid.
 6. The device of claim 1, further comprising a base that defines a first opening of the chamber, and wherein the plurality of structures, the chamber, and the base comprise a single ply of material.
 7. The device of claim 1, wherein the chamber has a bellows configuration.
 8. The device of claim 1, wherein the sealing portion includes a first surface having an adhesive, and the sealing portion defining a first opening of the chamber.
 9. The device of claim 8, wherein the tube connects to the chamber at a position spaced apart from the first opening defined by the chamber.
 10. The device of claim 1, further comprising a section device, a fluid trap, and an exhaust port, wherein the suction device is in fluid communication with the sealed treatment space, the fluid trap, and the exhaust port, and the fluid trap is fluidly positioned between the suction device and the exhaust port.
 11. The device of claim 1, further comprising a manual pump in fluid communication with the sealed treatment space to apply the negative pressure.
 12. The device of claim 11, wherein the manual pump is wedge-shaped and includes a spring that biases the manual pump to an uncompressed position.
 13. The device of claim 1, wherein the chamber is generally cylindrical and configured to treat a wound on a limb.
 14. The device of claim 1, wherein the plurality of structures configured for direct contact with the wound are positioned uniformly apart from one another.
 15. The device of claim 1, wherein the device is configured to treat the wound for a prolonged duration of a healing process.
 16. The device of claim 1, wherein the structures form a projection on the inside surface and a recess on an outside surface.
 17. The device of claim 1, wherein the chamber is conformable.
 18. The device of claim 1, wherein the plurality of structures configured for direct contact with the wound are positioned non-uniformly apart from one another.
 19. The device of claim 1, wherein the plurality of structures are embossed.
 20. The device of claim 1, wherein the therapeutic agent comprises an agent selected from the group consisting of antimicrobials, antibiotics, antifungals, and analgesics.
 21. The device of claim 1, wherein the chamber is movable over a range of positions, the range of positions including a first position in which the plurality of structures is spaced apart from the opening of the chamber, and the range of positions further including a second position in which at least some of the plurality of structures is positioned in the first opening of the chamber.
 22. The device of claim 1, wherein the plurality of structures covers at least 95 percent of the inner surface.
 23. A method of treating a wound, comprising: sealing the device of claim 1 to a periphery of the wound, applying negative pressure and distributing the negative pressure through the pathways; and maintaining the negative pressure to treat the wound.
 24. The method of claim 23, the method further comprising the step of applying a therapeutic agent to the wound.
 25. The method of claim 24, wherein the therapeutic agent is selected from the group consisting of antimicrobials, antibiotics, antifungals, and analgesics.
 26. The method of claim 23, wherein the device further comprises a suction device for applying the negative pressure, a fluid trap and an exhaust port, wherein the suction device is in fluid communication with the treatment space, the fluid trap and the exhaust port, and wherein the fluid trap is fluidly positioned between the suction device and the exhaust port.
 27. The method of claim 23, wherein the device further comprises a manual pump for applying the negative pressure, and wherein the treatment space is in fluid communication with the manual pump.
 28. The method of claim 27, wherein the manual pump is wedge-shaped and includes a spring that biases the manual pump to an uncompressed position.
 29. The method of claim 23, wherein the plurality of structures include first structures and second structures, the first structures having a first height dimension and the second structures having a second height dimension, and the first height dimension is greater than the second height dimension.
 30. The method of claim 23, wherein each of the structures in the plurality of structures is semi-rigid.
 31. The method of claim 23, wherein the plurality of structures intrude perpendicularly from the inner surface.
 32. The method of claim 23, wherein the plurality of structures that directly contact the wound are positioned uniformly apart from one another.
 33. The method of claim 23, wherein applying negative pressure includes conforming the inner surface to the wound.
 34. The method of claim 23, wherein the plurality of structures that directly contact the wound are positioned non-uniformly apart from one another.
 35. The method of claim 23, wherein the plurality of structures are embossed.
 36. A device for wound treatment, comprising: a wall being made of an impermeable material sufficiently thin to conform to a wound and including an interior surface, the interior surface defining a plurality of embossed structures configured to directly contact the wound and to create pathways for distributing negative pressure between the inner surface and the wound; a base coupled to the wall and including an adhesive arranged for sealing engagement with a patient's skin to form a sealed treatment space around the wound, wherein the plurality of structures intrude into the sealed treatment space from the interior surface of the wall; and a portal supported by the wall and being in fluid communication with the sealed treatment space so as to enable at least one of applying negative pressure to the treatment space and applying a therapeutic agent to the wound, wherein the device does not include a porous insert.
 37. The device of claim 36, wherein the base is disposed apart from the plurality of embossed structures.
 38. The device of claim 36, wherein the wall defines a bellows configuration including the plurality of embossed structures.
 39. The device of claim 36, wherein the plurality of embossed structures are positioned uniformly apart from one another.
 40. The device of claim 36, wherein the device is configured to treat the wound for a prolonged duration of a healing process.
 41. The device of claim 36, wherein the embossed structures form a projection on the inside surface and a recess on an outside surface.
 42. The device of claim 36, wherein the plurality of embossed structures are positioned non-uniformly apart from one another. 